[📖] Document more thoroughly the use case for `useContent` with current page's headings

[shairez]

Suggestion

It's not obvious from reading the regular docs (not API), that useContent can retrieve all the headings of the loaded index.mdx (and it's only working for mdx files, not tsx by the way)

The only place that kinda mentioning it is:
https://qwik.dev/docs/api/#usecontent

We need to add a dedicated section under Qwik City (as a standalone or under "nested routes" or "layouts" or something)

This is useful when you want to create sidebar links of the current page's headings

[AdrianRomanski]

@shairez I would like to take it as a first issue :) Then of course many more :D

[gioboa]

@AdrianRomanski go for it 👍 thanks

[iitzIrFan]

Hi @shairez @gioboa , can I take this issue as it has not been an update form @AdrianRomanski . So as per the issue we can add new section to the API reference file to explain how useContent can retrieve headings from .mdx files.
And also add an new file in the main documentation section. This file provides a user-friendly guide on using useContent to retrieve page headings, complete with an example, notes and use cases.

[gioboa]

That is sound great to me @iitzIrFan

[iitzIrFan]

@gioboa Thanks for your response and this the PR for review: #8073 :)

[AdrianRomanski]

I was almost sure that this task is finished